A 13-year-old premenarchial girl evaluated for abdominal pain was found to have a huge abdominopelvic cyst by ultrasound and CT Scan. She was managed successfully by laparotomy and excision of the non-ovarian huge cyst in toto, which was found to be a chylolymphatic mesenteric cyst. Chylolymphatic mesenteric cyst is a rare entity with variable clinical presentations and possible surgical implications in paediatric age group. Ultrasonography and CT scan suggest the diagnosis; however, histopathology is often required for confirmation. Complete excision of the cyst yields excellent results.